The issue here is that you are attempting to map ResourceLocation in the context of a ResourceStatus, but these two objects aren't directly related in the object model. The way it is currently mapped would indicate to EclipseLink that ResourceStatus has a composite relationship to ResourceLocation, which is not the case. You can make use of our extended API to get this working, though. Here's one way to do it:

Use an object to hold on to the ResourceStatus/ResourceLocation pairs, like this:

We will use a custom accessor that populates the ResourceStatusLocations objects based on List<ResourceStatus> and List<ResourceLocation> in the Response object (for marshalling), and populates List<ResourceStatus> and List<ResourceLocation> based on the ResourceStatusLocations objects during unmarshal. Something like this: